public class HTTPCalloutsDemo {
	
	public void callEXTcalc()
	{
		Http h=new Http();
		Httprequest req=new Httprequest();
		req.setEndpoint('http://allyservice.cognizant.com:80/CalcProject/CalculatorPS');
		String reqxml='';
			reqxml='<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:cal="http://calculator/">';
	   		reqxml+='<soapenv:Header/>';
	   		reqxml+='<soapenv:Body>';
	      	reqxml+='<cal:add>';
	        reqxml+='<arg0>10</arg0>';
	        reqxml+='<arg1>20</arg1>';
	      	reqxml+='</cal:add>';
	   		reqxml+='</soapenv:Body>';
			reqxml+='</soapenv:Envelope>';
		req.setBody(reqxml);
		req.setMethod('POST');
		Httpresponse res=h.send(req);
		
		String resXML=res.getBody();
		System.debug('response xml:::::::'+resXML);
		
		
		
	}

}